I have a 6 Volt sulfuric acid battery used to power a golf cart that has all the acid drained out, and the usual solution was to add more water to the battery however I am afraid that would not work this time since there is no acid left. Could I solve it by adding more acid from other batteries? or do I need to be accurate in the amount of acid added? or could I just solve it by adding water? If you could also give me an explanation as to how these batteries work and why adding water has any benefit I would appreciate it.
Depending on how long the battery has been sitting empty even adding electrolyte might not help.
Your best bet is to fill the battery with distilled water and put it on a charge, charge it for a couple of days if possible.
Get yourself a hydrometer (used for checking the specific gravity of your electrolyte) and check the water's gravities. After you charge the battery for awhile check them again. If the gravities start to rise, and the liquid is reasonable clear stop charging the battery and let it sit 12-24 hours. (If however the water turns cloudy/grey the battery is scrap get a new one).
After the battery has sat and cooled down, empty the water into a container, and neutralize with soda ash, or baking soda. BE CAREFUL even though what you put it was water, what will come out might/will be corrosive. Dispose of properly.
Now go to your local auto parts store and buy a box of battery electrolyte its usually sold as 1.28 spg, fill the battery with electrolyte re-charge until your gravities come up, and voila, use just re-conditioned a battery.
Be sure to wear rubber gloves / goggles or face shield and any other appropriate safety gear. Remember that when a battery charges it releases hydrogen sulfide gas which is explosive so no open flames sparks etc....
Of course the battery may only last your a couple of months or another year or so, and it may not even come back at all. But I have used this procedure with great success to revive old batteries....and squeeze a bit more life out of them.
Jeff Industrial battery specialist for 30 years.
Obviously handling sulfuric acid is hazardous. If all the acid leaked out, I would get a new battery, otherwise the acid will leak out again and possibly hurt someone or damage the vehicle.
If there is no acid, certainly adding water will not help. If you do add acid, the concentration of acid needs to be correct.
Lead-acid batteries do not contain pure sulphuric acid, but acid dilute with water. The concentration of acid can increase over time due to electrolysis of the water to hydrogen and oxygen gases. If the concentration of acid is too high (solution density above 1.19 g/ml), adding water to dilute the acid is beneficial.